1. Field of the Invention
The present invention relates to a tag affixed to a variety of articles and more specifically to a method and apparatus for making tags, a tag, and a system for managing articles to which the tag is affixed.
2. Description of the Related Art
With recent improvements in performance of copy machines and printers and in processing capabilities of personal computers, it has become more and more likely for bank bills and securities as well as a variety of documents such as passports, various documents of title, and certificates to be replicated; therefore, there is a desire for establishment of a technology that can highly accurately judge whether various documents are real or fake.
Further, conventionally, imitations of industrial products including so-called brand products have been manufactured and distributed, in which imitation tags have been replicated using a copy machine, a printer, etc. Furthermore, tags for agricultural products have been increasingly forged to deceptively label their place of production
In view of the above, a proposal has been made to make a hologram indicative of data of a commercial product and embedding the hologram around a mark that makes the product identifiable to enable determination of authenticity of the product, thereby preventing imitation of the product (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2001-100623).
Further, a proposal for a product verification system, which provides a body of a brand mark on a commercial product with an identification element having a memory whose stored information can be read by electromagnetic induction and stores in this memory information unique to the body of the brand mark so that product verification is made possible, whereby forging can be prevented, has been made (see, for example, JP-A No. 2002-117165).
On the other hand, when any one of a variety of commercial products is manufactured, a label or a tag recording information about the product is affixed. Therefore, a proposal has been made for performing printing by use of functional ink on, for example, a starch surface of an adhesive paper of the label, to enable confirmation of the authenticity of the label in a predetermined environment or by using a predetermined appliance (see, for example, JP-A No. 2002-103782).
Another proposal has been made to use a rewritable label allowing erasure and writing of information as a tamper-proof invoice form and shipment form, to write a serial number on the rewritable label so as to be non-erasable and write the serial number and commercial product information of a supplier on the invoice form and write part of the contents of the invoice form as well as new product information and the serial number on the shipment form in a tamper-proof manner, thereby preventing deceptive labeling (see, for example, JP-A No. 2004-94510).
However, these proposals necessitate creation of a hologram or implementation of special printing and require relatively expensive components such as an IC tag or a rewritable label. Further, despite such expense and special processing, they cannot always be capable of adequate prevention of imitation, deceptive labeling, etc.
That is, whereas a label or a tag to be affixed to a commercial product would be most inexpensive if paper is used as a material thereof, in comparison therewith, all of these proposals would lead to an increase in costs.
As for cases where paper is used as the material, a proposal has been made for partitioning a predetermined area of a tag into numerous quadrilateral regions while utilizing randomness in degree of transparency of the paper owing to randomness in intertwining of fiber materials of the paper, detecting transparency degrees of six quadrilateral regions selected at random from among these regions, and storing these detected transparency degrees as information together with addresses of these quadrilateral regions so that the respective quadrilateral regions specified by the stored information may be detected, to compare a result of this detection to the transparency degrees given by the recorded information, and to thereby determine whether the labeling is real or fake (see, for example, Japanese Patent Application Publication (JP-B) No. 6-16312).
However, in the proposal of JP-B No. 6-16312, real-or-fake determination requires the use of recorded information, and thus the proposal, has a problem in that it cannot be conducted by a simple operation at an arbitrary timing. That is, the proposal has a problem in that real-or-fake determination can be conducted only if particular data is available or only where such data can be read.